Farmers first reached Orkney on boats that took them across the narrow – but treacherously dangerous – Pentland Firth from mainland Scotland. These were the people of the New Stone Age, and they brought cattle, pigs and sheep with them, as well as grain to plant and ploughs to till the land. The few hunter-gatherers already living on Orkney were replaced and farmsteads were established across the archipelago.
There are very few places and or peoples that have settled proper terra nullius. Entirely uninhabited regions.
Off the top of my head I can really only think of two: Maoris in New Zealand (and OK, all of the associated expansion across the Pacific Islands to Hawaii etc) and the Portuguese on Madeira. There’s even significant doubt now as to whether the Amerinds were the first to the Americas via Siberia.
The point being that almost all of the “it’s our land, the invaders stole it from us” stuff is in fact just one group of descendants of land thieves complaining about being usurped by a later set of such.
And yes, this does indeed describe such places as Southern Africa. The Bantu got there only marginally before the Dutch, indeed, for the area beyond the Fish River, afterwards. Hottentots (or perhaps we should call them Kung! now?) had the place before either: and Pygmies much of the area further north.
Or if you prefer: there’s nothing unique about the European expansion of the past 500 years. The technology and the skin colour perhaps, but not much else.